VME Modules Research Articles

Lower contrast volumes with minor protocol changes enhance 64-channel CTA imaging in peripheral vascular disease

A new data acquisition system (DAQ) for bulk μSR and low-energy μSR (LE-μSR) has been developed at PSI. It is based on commercial and in-house VME modules, and on the MIDAS DAQ software library. The system is able to cope with the different needs of the various PSI μSR spectrometers, which was not possible with the existing CAMAC and ORTEC's pTA-clock based DAQ systems. The VME clock is a 64-channel CAEN V1190 TDC, using the CERN HPTDC chip, with programmable time resolution of 25, 100, 200 or 800 ps. The TDC onboard memory is continuously read through the VME bus by standard PC's or dedicated servers, using a 1-Gbit/s SIS3100/1100 VME–PCI interface. Detector rates are independently monitored using a 32-channel SIS3820 scaler module. In-house developed modules comprise an 8-channel constant fraction discriminator CFD950, a CD950 clock divider, an 8-channel linear fan-out SP950, a 16-channel NIM-ECL level converter LC950, and a programmable coincidence module FC950. All modules feature a superior performance compared to commercially available devices which allows their use also in the planned high-field μSR spectrometer where a time resolution of about 100 ps is envisaged. A special external hardware logic is no longer required, since the system can deal with a rate total of 5 MHz which is sufficient for μSR spectrometers with high event rate in their active veto systems.

Polarization measurement in the COMPASS polarized target

Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and −53% as the average in the target cells.

TASS—Trigger and Acquisition System Simulator. An interactive graphical tool for DAQ and trigger design

Trigger and Acquisition System Simulator is a simulation program with graphical and interactive interface. It reproduces in a realistic way the commercial Nim, Camac and Vme modules: both the front panel appearance and the electrical and logical behaviors are simulated.

The DAQ system with a RACEway switch for the PHOBOS experiment at RHIC

The PHOBOS data acquisition system based on a RACEway switching network is described. Occupying a single VME crate, the system utilizes 22 PPC750 CPUs working in parallel to compress data from 135 168 silicon pad detectors and an UltraSPARC VME host for event building and data storage. Lossless Huffman coding is used for compression; this reduces the event size fourfold. The two-host disk array is used to stage data before sending them over Gigabit Ethernet to the Relativistic Heavy Ion Collider (RHIC) central computing facility. All trigger and control logic is formed using universal programmable logic VME modules, which can be programmed in situ, even when the system is running. The event building and run control software is written using the ROOT framework. The slow control and configuration makes use of an Oracle database to store configuration and monitoring parameters. The system has been taking data from the PHOBOS experiment at RHIC since June 2000. The achieved data-taking rate is 280 events/s or 28 MB/s, with additional disk arrays it can potentially reach 80 MB/s.

Development of a new TDC LSI and a VME module

A new TDC LSI and a TDC VME module have been developed. The TDC LSI (called AMT-2) is developed for precision muon trackers of the ATLAS experiment. The AMT-2 chip has 24 input channels and 280-ps rms resolution. It is processed using 0.3-/spl mu/m CMOS technology. The TDC module (called AMT-VME) has 64 channels and a wide timing range (/spl sim/100 /spl mu/s) with a 0.78-ns/bit timing resolution. The module also contains a digital signal processor for controlling data acquisition and manipulating data. Acquired data are read out through the VME bus via a dual-port memory bank. The designs of the chip and the module are presented, and a test result is shown.

A high-data-transfer-rate VME system for TCP-IP remote real-time control of the ITER in-vessel vision system

This paper describes the control and data acquisition system (CADAS) for the in-vessel vision system (IVVS) for ITER, which imposes special design requirements due to its reactor characteristics. CADAS provides remote real-time control of the motors (by TCP-IP), fast data acquisition (20 bytes/pixel at 100 kpixels/s), error management and sustainable network data transfer rates (by TCP-IP). It is composed of a supervisory workstation connected by a 100 Mbit/s Ethernet channel to a remote VME crate, housing a board based on a PowerPC604R CPU running LynxOS, and two on-site developed intelligent modules. The architecture of these VME modules as well as the operation software and the application protocol are described. The test results are presented as well as an image obtained during the test procedures performed at the ENEA-Frascati Laboratory.

CHIMERA data acquisition and computational system using DSP-based VME modules

We have built and tested a computational unit for on-line processing of special algorithms to be embedded in the central processing unit VERSAmodule Eurocard (CPU VME)-crate of the CHIMERA data acquisition system. The computational unit consists of a number of VME digital signal processor (DSP)-based commercial boards delivering 720 MFlops/board.

The muon pretrigger system of the HERA-B experiment

One of the main goals of the HERA-B experiment at DESY in Hamburg, Germany, is to study the properties of B-mesons with the emphasis on CP violation. B-mesons are produced in hadronic interactions of a 920-GeV proton beam with an internal wire target. An effective bunch crossing rate of about 8.5 MHz leads to about 200 charged tracks per event. Therefore, a highly selective and efficient trigger system providing high suppression of background events is required. The HERA-B trigger system consists of four levels. A rate reduction factor of 200 is aimed at by the first-level trigger (FLT). The muon pretrigger system, as a part of the FLT, is a modular system consisting of about 100 large-size VME modules of three different types: the pretrigger link board (PLB), the pretrigger coincidence unit (PCU), and the pretrigger message generator (PMG). The data rate processed by the pretrigger system is about 19.5 GByte/s. The PLBs process digitized hit information in eight independent electronic channels in parallel. Every electronic channel handles 32 bits of hit information received from the front-end driver buffer system. Optical links operating at 800 Mb/s transmit the data after serialization to PCUs, which calculate coincidences using complex programmable logic devices. The PMGs transform this coincidence information into messages for the FLT processors. The concept and design as well as results of the muon pretrigger running at HERA-B are presented.

Control and data acquisition systems for high field superconducting wigglers

This paper describes the control and DAQ system of superconducting wigglers with magnetic field range up to 10.3 T. The first version of the system controls a 7 T superconducting wiggler prepared for installation at Bessy-II (Germany). The second one controls a 10 T wiggler which is under testing now at the SPring-8 site (Japan). Both systems are based on VME apparatus. The set of specialized VME modules is elaborated to arrange wiggler power supply control, full time wiggler monitoring, and magnetic field high accuracy measurement and field stabilization. The software for the control of the wigglers is written in C language for VxWorks operation system for a Motorola-162 VME controller. The task initialization, stops and acquisition of the data can be done from the nearest personal computer (FTP host for VME), or from the remote system as well.

Design and performance of a data acquisition system for VUB-PET

A flexible and high-speed VME-based data acquisition system (DAQ) has been designed to process data from the University of Brussels (VUB) small-animal positron emission tomography (PET) system. The core tasks of the system are performed by two custom VME modules: a trigger module and a fast readout module (FRO). Following the detection of a valid coincidence event by the trigger unit, the raw data from all analog-to-digital converter channels involved are read out simultaneously via a FRO. An onboard digital signal processor (DSP) processor checks and calibrates these data. To increase the transfer throughput of the list mode data to a SUN Ultra Sparc 1 workstation, the DSP processor compresses the data format to a 6-byte data packet per event. The maximum average sustained acquisition rate of the system is 200000 counts per second (cps), while peak rates up to 2 Mcps can be handled. The DAQ also provides online measurement of the random event rate, the single event rate and event losses due to electronic dead time.

VME crate interconnection through the SCI network in large data acquisition systems

The possibility of using PCI Mezzanine Cards (PMCs) in VME modules opens new options for interconnecting crates by means of high-speed interconnection networks (Scalable Coherent Interface (SCI), ATM, Fiber Channel, etc.). These new technologies offer major benefits in the construction of large data acquisition networks where the number of VME crates is important. In this paper we explain how to use an SCI to easily connect VME crates and take advantage of the new scalability offered by SCI.

Construction of a compact DAQ-system using DSP-based VME modules

A data-acquisition (DAQ) system based upon the SRARC digital-signal-processor (DSP) has been developed. Either one or two DSPs are mounted onto VME boards, WS2126. VME-to-VME data transfer utilizes SHARC links (33.7 MB/s of measured transfer rate), routed onto a front panel of the WS2126 by I/O piggy pack modules, WS9002. The system has been designed for readout of 81,920 FADC (flash analog-to-digital converter) channels at a maximum trigger rate of 500 Hz. This system could be accomplished in a compact setup of four FADC readout VME crates and one master-control VME crate (for event-building and run-control). The system was tested for readout of the BELLE Si vertex detector (SVD).

Development of the central trigger system for the BELLE detector at the KEK B-factory

In this paper, we describe the design and development of the central trigger system (GDL) for the BELLE detector at the KEK B-factory. The GDL consists of four types of single width 6U VME modules (ITD, FTD, PSNM and TMD) which are designed using the programmable logic techniques of Xilinx FPGA and CPLD. Individual and combined performance tests of these modules are done and it is confirmed that the GDL functions as expected.

The trigger system of the NOMAD experiment

The NOMAD trigger system is described in the present paper. It is made up of a large area plastic scintillator veto system, two trigger scintillator planes inside a 0.4 T magnetic field and their associated trigger electronics. Special features of the system consist of the use of proximity mesh photomultipliers which allow the trigger scintillators to operate in the magnetic field, and the use of custom-built VME modules which perform the trigger logic decisions, the signal synchronisation and gate generation, event counting and livetime calculations. This paper also includes a description of each of the NOMAD triggers, with their calculated and measured rates, efficiencies and livetimes.

Multiple DSP system for real time parallel processing and feedback control on fusion experiments

This paper describes a specially designed system for real time parallel processing and feedback control on fusion experiments. The system is being implemented in PCI and VME modules, based on an array of four synchronizable DSPs, with 1 Mbyte of global RAM, 12 bits resolution, four analog inputs with sampling frequency up to 40 MSPS, two analog or waveform generator outputs with an update rate up to 100 MSPS, eight digital opto-coupled inputs/outputs and one external global trigger optical input. The user interface appears as a virtual instrument from LabView for Windows.

The 32 bit timing unit of a real-time event-based control system for a nuclear fusion experiment

This paper describes the innovative timing unit of a distributed, expandable, real-time, event-based control system for a nuclear fusion experiment. This system is being designed in a tree-type topology, based in VME and CAMAC format modules that produce the timing signals required for the safe operation of the experiment diagnostics and digitizers. It also performs the broadcasting, processing and recording of the occurrence of externally generated events for real-time control purposes. The timing unit has been implemented in a field programmable gate array, providing flexibility and the ability to upgrade the design. The timing signals can be defined with 32 bit resolution to produce signals from 100 ns width and to about 430 s maximum duration with 500 ns accuracy, and will provide the possibility of immediate event processing.

A single-board VME mössbauer-spectrometry module

A VME module is described to interface a mössbauer spectrometer to a computer system. It is used at the IRI mössbauer spectrometry laboratory to control 12 spectrometers. Six mössbauer modules, with additional dual ported memories, are housed in a VME-rack. Features: Generation of computer composed functions and digitizing of function-related signals, multi-channel scaling, pulse height analysis, and current integration as an optional detection technique. Functions representing a desired velocity pattern are digitally stored in the function memory. They are converted to analog using a 12-bits Digital to Analog Converter (DAC). The output of the DAC is the voltage reference for a mössbauer drive unit that drives a velocity transducer carrying a gamma radiation source. Multi-Channel Scaling (MCS) is used to measure a mössbauer spectrum. Internally a function time-base and a multi-scaler time-base are generated. A Pulse Height Analyses (PHA) facility, using a 12-bits Analog to Digital Converter (ADC), is implemented to measure the gamma spectrum of the radiation source. A mössbauer transition energy can be selected in a handsome way using this feature. An additional task of the ADC is digitizing function related signals, such as the velocity-feedback signal. If this signal is digitized, the velocity reference-function could be modified by software to correct a deviation in the source movement. For measurements with very strong gamma sources the Current Integration Technique (CIT) is implemented. Instead of a voltage to frequency-converter, formerly applied for this type of experiments, the ADC can be used for signal digitizing in this mode of operation.

Multi detector input and function generator for polarized neutron experiments

In this paper a VME module is described for static or stroboscopic measurements with a neutron scattering instrument, consisting essentially of a series of up to 64 3He neutron detectors around a sample environment. Each detector is provided with an amplifier and a discriminator to separate the neutrons from noise. To reduce the wiring, the discriminator outputs are connected to the module by coding boxes. Two 16-inputs to one-output coding boxes generate serial output codes on a fiber optic connection. This basically fast connection reduces the dead time introduced by the coding, and the influence of environmental noise. With stroboscopic measurements a periodic function is used to affect the sample surrounded by a field coil. Each detected neutron is labeled with a data label containing the detector number and the time of detection with respect to a time reference. The data time base can be programmed on a linear or a nonlinear scale. An external source or an attribute of the periodic function may generate the time reference pulse. A 12-bit DAC connected to the output of an 8 K, 16-bits memory, where the pattern of the current has been stored before, generates the function. The function memory is scanned by the programmable function time base. Attributes are set by the four remaining bits of the memory. One separate detector input connects a monitor detector in the neutron beam with a 32-bit counter/timer that provides measuring on a preset count, preset time or preset frame.

An integrated computer control system for the ANU linac

One facet of the installation of the superconducting linac at the ANU is the need for computer control of a variety of systems, such as beam transport, resonator RF, cryogenics and others. To accommodate this, a number of control interfaces (for example, analogue signals and RS232 serial lines) must be employed. Ideally, all of the systems should be able to be controlled from a central location, remote from the actual devices. To this end a system based around VAX computers and VME crates has been designed and is currently being developed and implemented. A VAXstation is used to issue control messages and perform high-level functions, while VME crates containing appropriate modules (primarily DACs, ADCs and digital I/O boards) control the devices. The controllers in the VME crates are AEON rtVAX modules running a real-time operating system. Communication with the VAXstation is via DECnet, on a private ethernet to allow communication rates unaffected by unrelated network activity and potentially increasing the security of the system by providing a possible network isolation point. Also on this ethernet are a number of terminal servers to control RS232 devices. A central database contains all device control and monitoring parameters. The main control process running on the VAXstation is responsible for maintaining the current values of the parameters in the database and for dispatching control messages to the appropriate VME crate or RS232 serial line. Separate graphical interface processes allow the operator to interact with the control process, communicating through shared memory. Many graphics processes can be active simultaneously, displaying either on a single or on multiple terminals. Software running on the rtVAX controllers handles the low-level device-specific control by translating messages from the main control process to VME commands which set hardware outputs on VME modules. Similarly, requests for the value of a parameter result in the rtVAX program interrogating VME input modules, and returning the result to the main control process. In the near future, this system will be extended to control most of the 14UD accelerator, in addition to thelinac. At present the system also controls one of the two ion sources that provide beam to the 14UD.

New data acquisition system for the focal plane polarimeter of the Grand Raiden spectrometer

This paper describes a new data acquisition system for the focal plane polarimeter of the Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP) in Osaka, Japan. Data are acquired by a Creative Electronic Systems (CES) Starburst, which is a CAMAC auxiliary crate controller equipped with a Digital Equipment Corporation (DEC) J11 microprocessor. The data on the Starburst are transferred to a VME single-board computer. A VME reflective memory module broadcasts the data to other systems through a fiber-optic link. A data transfer rate of 2.0 Mbytes/s between VME modules has been achieved by reflective memories. This rate includes the overhead of buffer management. The overall transfer rate, however, is limited by the performance of the Starburst to about 160 Kbytes/s at maximum. In order to further improve the system performance, we developed a new readout module called the Rapid Data Transfer Module (RDTM). RDTM's transfer data from LeCroy PCOS III's or 4298's, and FERA/FERET's directly to CES 8170 High Speed Memories (HSM) in VME crates, the data transfer rate of the RDTM from PCOS III's to the HSM is about 4 Mbytes/s.